Global navigation satellite systems (GNSS) use wireless signals transmitted from medium Earth orbit (MEO) satellites to provide position and velocity information of GNSS receivers. Examples of currently operational GNSSs include the United States' Global Positioning System (GPS), the Russian Global Navigation Satellite System (GLONASS), the Chinese BeiDou Satellite Navigation System, and the European Union's (EU) Galileo. Today, GNSS receivers are used in a wide range of applications, including navigation (e.g., for automobiles, planes, boats, persons, animals, freight, military precision-guided munitions, etc.), surveying, mapping, and time referencing. Further applications for GNSS technology will become available as new techniques for improving GNSS accuracy are introduced.
One source of GNSS inaccuracy is multipath interference, which is caused by wireless signals reflecting off objects surrounding the GNSS receiver, such as mountains, trees, buildings, ground, water, persons, etc. Multipath signals arrive at the GNSS receiver later than the line-of-sight (LOS) signal, and although multipath signals with large time delays can be filtered out, multipath signals with shorter delays often distort the correlation function shape used for time delay estimation. Current methods for mitigating multipath interference are insufficient. Accordingly, new systems, methods, and techniques for mitigating multipath interference are needed.